1. Field of the Invention
The present invention relates to a carrier body for a catalytic converter, including a honeycomb body, a jacket tube and a sleeve disposed between the honeycomb body and the jacket tube. The invention also relates to a method of producing the carrier body. Such catalytic converters are preferably used in exhaust systems of internal combustion engines, in particular of motor vehicles.
A method of producing a sheathed honeycomb body is described in International Publication No. WO 99/37896. The sheathed honeycomb body has layers of sheet metal, at least some of which are structured, and is produced by laminating and/or winding, so that the honeycomb body has channels through which a fluid can flow. That honeycomb body is surrounded by a jacket tube. The honeycomb body and the jacket tube have a different thermal expansion behavior due to their different material properties and due to different temperatures during operation. It is therefore endeavored to avoid a rigid connection between the honeycomb body and the jacket tube at least at one end region of the honeycomb body. For that reason, the sheathed honeycomb body is formed with a sleeve which is intended to ensure that direct brazed connections between the honeycomb body and the jacket tube are avoided in the at least one end region of the honeycomb body, in spite of production tolerances of the jacket tube and the honeycomb body. During the production of such honeycomb bodies, some points of contact between the honeycomb body and the sleeve are connected to one another, more or less arbitrarily, but many of such points of contact remain unconnected. Although thermal stresses between the jacket tube and the honeycomb body are avoided in that way, no defined joining of the honeycomb body to the sleeve is achieved.
However, a sheathed or encased honeycomb body of that type, which is used as a catalyst carrier body in an exhaust system, is subjected not only to thermal loading but also to dynamic loading. That means that the displaceably disposed end region of the honeycomb body can be induced to oscillate. Undefined fastened points of contact may become detached and unfastened sheet metal layer ends may flap freely, which may lead to the detachment of the catalytically effective coating. Furthermore, there is a risk of those freely flapping subregions being detached from the honeycomb body, blocking neighboring channels or causing damage in neighboring components of the exhaust system.